rainwater capture basic math how to capture the...

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rainwater capture basic mathIf you want to figure out how large your rain garden should be, use this basic calculation.

Gallons of Water ÷ 7.48 = Square Feet of Rain Garden (at 12” deep)For example, to capture 620 Gallons, how big should you dig?

620 Gallons ÷ 7.48 = 83 Sq. Ft. area (at 12” deep)620 Gallons ÷ 7.48 = 166 Sq. Ft. area (at 6” deep)

If your rain garden (aka swale) is 10' wide and 8-1/2' long, its area (10’ x 8.5’) is 85 squarefeet. So at 12” deep, it will hold about 620 gallons of rainwater. If you dig it down just 6”deep, your rain garden will hold only half of that, or just 310 gallons of water. With shallower swales, you may want more, or wider rain gardens. If you make your swaledeeper, you can capture more water in a smaller footprint.

HOW MUCH WATER RUNS OFF THE ROOF?The shape of your roof doesn't matter. A pitchedroof and a flat roof have the same footprint and thesame amount of rain falls on the area no matter itsshape. Just measure the outside edges and calcu-late the area.

Area = length of side a x length of side bFor complicated roofs, divide into squares thenadd up the area of each square.

Rainfall (in inches) x Square Feet x .62 =Gallons of Rain Water

If your roof is 1,000 square feet here's how muchwater runs off it:

1” (rainfall) x 1,000 (sq. ft.) x .62 = 620 gallons 5” (a big storm) x 1,000 x .62 = 3,100 gallons 15” (one year's total rainfall) x 1,000 x .62 =

9,300 gallonsIt adds up quickly, even in dry areas. Try to saveas much as you can in your garden!

HOW MUCH WATER COMES OUT OF ONEDOWNSPOUT?Imagine the water from your roof splits into twodownspouts.

Your Roof Area is 20' x 40' = 800 sq. ft.If half of the water goes into each downspout,then the roof size for one downspout is:

800 sq. ft. ÷ 2 = 400 sq. ft.Now calculate how much water that is in gallons.

400 sq. ft. x 1” x .62 = 248 gallons(of water, per inch of rain, from each

downspout). You can use these calculations to determine how much water comes off of any hard surface (patio, driveway, roof, sidewalk, etc.)

Excerpted from The Drought Tolerant Garden: Los Angeles County Handbook, © 2012, Los Angeles County

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soilmaking the sponge

So how do I change a BRICK into a SPONGE? Living soil remediation is theanswer. It's not fertilizer, but it is food for the soil. When that food is digested bythe organisms, it becomes food for the plants!

LIVING SOIL REMEDIATION

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ADD OXYGEN by opening up the soil. Once the spongy soil structure has beencreated, you will not want to break up the soil again. But to get things started, you must beak a few eggs --- or break a little soil. You can rototill it, auger it, or dig it up with a shovel (or jackhammer!). Sometimes all it takes is apitchfork plunged into the ground and pulled back and forth.

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ADD WATER and LIFE. You can add good compost, worm castings, and/orcompost tea. All of these are full of the living microbes that will do the hard workof bringing your soil back to life. Spread them on, give them some water, andthen…

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FEED YOUR SOIL ORGANISMS (not your plants)! They like to eat organic mat-ter, so give them a nice thick blanket of mulch (3” at least). Add water as needed,and your soil will be healthy and happy in no time, ready for your plants!

join the soil party! Living soil is alive. A teaspoon of good garden soil contains billions of invisible bacteria, several yards of equally invisiblefungal hyphae, several thousand protozoa and a few dozen beneficial nematodes.

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“soil lasagna” recipe(aka Sheet Mulching)

Ingredients: • SHOVELS & RAKES• BINS FOR REMOVED GRASS

AND SOIL (WARM SEASON TURF GRASS ONLY)

• LANDSCAPE FLAGS• COMPOST OR WORM CASTINGS• MULCH

(FRESHLY SHREDDED TREE TRIMMINGS WITH LEAVES ARE BEST)• PAINTERS PAPER OR BIG SHEETS OF CARDBOARD

(IT SHOULD BE CLEAN)• HOSE WITH SPRAY NOZZLE• WATER (LOTS!)

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Deal with the turf grass you have. If it's Fescue (cool season), say goodbye,give it a good soaking of water and go to Step 3.

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If it's the other kind (any mixture that includes Bermuda or St. Augustine)remove and dispose of soil at least 8” deep, but preferably 10” or more to be sure it’s all gone. If you can’t hand remove, rent a sod cutter.

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Dig back 12” - 24” from any hard surfaces and building foundations toa depth of 8” - 10.”

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Flag all your sprinkler heads so you can find and adjust or remove them later.

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Add LIFE! Spread out a 1” deep blanket of compost or worm castings.

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Water the soil so the paper will stick to it.

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Roll out paper or cardboard. Be sure to overlap all edges by at least 6” - don't leave any bare soil! If necessary, to prevent tearing and gaps, use two layers of paper.

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Water well - really soak the paper/cardboard.

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While the paper/cardboard is wet, gently rake out a thick blanket of mulch (4” to 6”) over everything. Keep watering while you do this - you want the mulchto be really wet at first.

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Admire your work.

That's it! Now the LIFE you added will get to work, turning it all into delicious,healthy living soil. When you're ready to plant, just dig a hole right into it, cuttingthrough the paper/cardboard (if it's still there) and plant right into the yummy soil.


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successful plantingrecipeIngredients:• TOOLS: shovel, hand trowel, hose• PLANTS • COMPOST • MULCHFeeling Adventurous? Try the more advanced planting approach in55

and add these to your list: MYCORRHIZAE (not for grasses) FISH EMULSIONor WATER SOLUBLE HUMATES

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Dig a hole! Don't dig it any deeper than therootball of the plant. Do dig at least a little bitwider than the plant to loosen the surroundingsoil. If you accidentally dig too deep, be sure toput the soil back in and tamp it down firmlybefore moving on, to give your plant a solid base.

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Throw in some compost or worm castingsno more than 1” deep - along the bottom of thehole. Never put mulch in a hole!

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Fill the hole with water TWICE, and allow it todrain completely each time. This will take a longtime, unless your soil is really sandy. Start dig-ging the next hole, or take a break.

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Submerge the rootball in a bucket of water untilair bubbles stop bubbling up. It's probably easier

to keep the plant in its container but ok if you takeit out - just be careful with the delicate roots.

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Add fish emulsion or soluble humate to thewater (follow label directions). Dust the rootballwith a mycorrhizae inoculant (only if the plantsare woody, so don't bother with the grasses).

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Place plant in hole, make sure the root collar(that's where the roots join the stem or trunk) isa bit (1/2” - 1”) higher than the surroundingsoil/existing grade. This is super importantbecause we don't want the plant to get chokedby the surrounding soil.

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Fill the hole with water one more time (thistime with the plant in it) and let it drain completely.

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Now fill the hole with the soil you dug out(not with fancy potting soil!), making sure thesoil slopes away from the root collar. Tamp thesoil down (use your feet, but be gentle) so theplant doesn't move around.

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Don't create a bowl around the plant. Really!Your plant doesn't need it and it might make amoat that would drown your drought tolerant plant.

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Water the soil all around the plant one moretime, and deeply. And have a drink yourself!

NOW THAT YOUR SOIL IS HAPPY you are ready to plant! It's almost as easy as digging a hole, but a little extra love will help. By following these simple steps, you will get your plants' roots growing properly, quickly spreading into the living soil and making friends with the other drought tolerant plants. Strong rootsmake strong plants, and this is especially important in dry environments.

What's with all the water at planting time? There are three reasons:DRAINAGE If the water does not drain within an houror so, it's probably not a good place to plant a droughttolerant plant until you fix the compaction.

SOIL PARTY By watering so thoroughly, you are waking up any microbes that might be in the surrounding soil.

PLANT SHOCK The major reason plants suffer fromplanting shock is that the dry soil around the new plants wicks water away from their rootball, sending the plant

into shock from which they never recover. By watering thesurrounding soil, you reduce the probability of plant shock.

“Hey, where's the fertilizer?” you may ask. Dry climategardens don't want nutrient rich (i.e. fertilized) soil. Itcould make them grow too fast, use too much water, orjust make them weak and sickly. By following our livingsoil remediation instructions you've made healthy, livingsoil for your plants - just add rainwater and that's allthese plant need! Really. Let the soil microbes do all thework to keep your plants strong, healthy, and continu-ously drought tolerant.

right plant right place


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check your soil type(an easy way to figure out your soil type)

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rainwater capture basic math how to capture the...

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